tasks a-s

Task/Queue-Usage/Icon/queue-usage.icon

@@ -0,0 +1,18 @@
+procedure main(arglist)
+queue := []
+write("Usage:\nqueue x x x - x - - - - -\n\t- pops elements\n\teverything else pushes")
+write("Queue is:")
+every x := !arglist do {
+   case x of {
+      "-"     : pop(queue)  | write("pop(empty) failed.")    # pop if the next arglist[i] is a -
+      default : put(queue,x)                                 # push arglist[i]
+      }
+   if empty(queue) then writes("empty")
+   else every writes(!queue," ")
+   write()
+   }
+end
+
+procedure empty(X)        #: fail if X is not empty
+if *X = 0 then return
+end